Various at-home oral care systems for whitening teeth are available to consumers. These include whitening trays, pens, strips, mouth rinse, and toothpaste. Some products provide printed reference cards of different tooth shades to help consumers track their whitening progress. However, such cards are inconvenient because the consumer must make multiple comparisons in an attempt to find the one card that best matches the color of the consumer's teeth. Additionally, because such cards rely on the consumer's selection of a tooth and their judgment of a best match, the results are subjective. Further, because the consumer may attempt to use the cards under different lighting conditions, the results may vary over time due to changes in color and intensity of ambient lighting.